The invention relates to on-the-fly automated document inspection and optical character recognition. More specifically, the invention relates to document quality control systems and methods that examine particular regions of documents.
Today""s digital printing systems are capable of printing documents that include regions of variable content, such as checks, bills, and advertising form letters, at very high rates. The process is similar to a more complex, large-scale, high-speed mail- or print-merge as can be performed with many of today""s word processors and databases. As a result of the high speeds at which these documents are printed, an error in one document of a print job can create a cascade of errors in subsequent documents. Depending on the nature of the errors, the entire print job following the first erroneous document might have to be scrapped if the error were undetected, which could be very costly. Thus, document inspection systems have been developed to check the regions of variable content to be sure the appropriate information is being printed in a given document.
Documents whose regions of variable content appear in the same location from document to document in a print job are adequate for the purposes of those who create and use them. However, there is a desire in the industry to run print jobs including documents that have variable content in different locations from document to document. This provides much more flexibility in the creation of form letters, printing of bills and statements, and the like. This also allows the inclusion of documents of very different types in the same print job. For example, a utility bill could be printed immediately after an advertising form letter, which could be followed by a bank statement. With such flexibility, a printing system could be connected to a network, such as a wide area network (WAN) or the Internet, to receive documents from a wide variety of clients for printing on demand. However, current document inspection systems are incapable of handling inspection of documents whose variable content appears in different locations from document to document in a print job.
Current systems check documents whose regions of variable content appear in the same locations from document to document in a print job. They work well, and the documents produced by high-speed printing systems are adequate for the needs of those who create them; but the documents are inflexible and, in the case of form letters, are impersonal. Thus, the printing of documents including regions of variable content in different locations from document to document in a print job cannot be automatically inspected using current technology and is currently somewhat risky since there is no easy way to prevent potentially costly printing errors.
Our inventive method and apparatus overcome the limitations of currently available document inspection systems by allowing inspection of regions of variable content whose locations vary from document to document in a print job. The location of a region under inspection of a document is determined, and an optical imaging system captures an image of the region under inspection. The image can be of the region under inspection alone, in which case the location of the region under inspection is sent to the optical imaging system prior to image capture. Alternatively, the optical imaging system can capture the entire document and the location of the region under inspection can be used to extract the relevant portion of the document image for analysis. The analysis of the region under inspection determines whether the region under inspection meets predetermined criteria. If the predetermined criteria are not met, then a discrepancy notation action can be taken. Depending on the type and degree of the discrepancy, the printing system can be stopped, the failure to meet the predetermined criteria can be logged and the printing system allowed to continue, the document that is erroneous can be diverted to a scrap pile, or another appropriate action can be taken. The predetermined criteria can include print density, other characteristics of the printing, and desired content of the region. Any of these criteria can be document specific.
The optical imaging system is preferably mounted in a printer of a digital printing system. However, the optical imaging system can also be mounted in a finishing system, or another location where it has access to the printed document.